PROJECT SUMMARY Pregnant women and their developing fetuses are particularly vulnerable, making life-course research, particularly regarding environmental exposures, highly important. However, traditional research of environmental exposures during gestation focused on one exposure at a time with limited results. Recently, the concept of the ?exposome,? or the measurement of the totality of one?s exposures has emerged, emphasizing the importance of considering as many of one?s exposures as possible. The exposome consists of three domains: the internal, specific external, and general external. The internal comprises the ?omics? technologies while the specific external comprises exposures such as environmental contaminants and the general external comprises social factors and stress. In this project, I endeavor to combine multiple measures of the specific external environment, specifically pesticides and air pollution, with aspects of the general external environment such as measures of socioeconomic status, along with measures of greenspace, during the prenatal period. I will investigate the association of this complex combination of exposures with the adverse pregnancy outcomes, preeclampsia and structural birth defects. Preeclampsia is a condition affecting 5% of pregnant women in the United States and is a major cause of maternal and neonatal mortality and other adverse birth outcomes. In previous work, we also observed an association between preeclampsia and selected structural birth defects. Birth defects affect roughly 3% of births in the United States and are the top cause of infant death. Etiologies of both preeclampsia and birth defects remain mostly unknown and research regarding environmental risk factors of both is limited. Thus, I will utilize the rich data available in a large birth cohort from the San Joaquin Valley in California, a region of one of the highest agricultural pesticide use areas and high air pollutant levels in the US, to investigate the association between this combination of environmental exposures with preeclampsia and the joint outcome of preeclampsia and birth defects.